The DSCOVR satellite orbits around the Lagrangian point L1 between the Sun and Earth. We can say the DSCOVR satellite lies between the Sun and Earth, but it is not exactly between them.
Flat-Earthers discovered images taken by the DSCOVR satellite showing the Moon in front of Earth and a solar eclipse shadow on Earth’s surface. Then they concluded it should be impossible if DSCOVR is really between the Sun and Earth. In reality, the DSCOVR satellite is not exactly between the Sun and Earth. It orbits a point between the Sun and Earth.
The Lagrangian point L1 is a point between Earth and the Sun, where the gravity of the Sun affects a body by the same strength as the gravity of the Earth. A satellite can orbit this particular point, so the satellite will roughly lie between Earth and the Sun. We call such an orbit a halo orbit, or more generally, a Lissajous orbit.
DSCOVR several times captured the image of the Moon in front of Earth. Flat-Earthers claim an eclipse should occur during the capture due to their incorrect assumption that the satellite is exactly between Earth and the Sun.
On the other hand, DSCOVR has also captured the Moon’s shadow on Earth during a solar eclipse. Flat-Earthers incorrectly claim the Moon should appear in front of Earth in the picture. Again, this is due to their wrong assumption that DSCOVR lies exactly between Earth and the Sun.